1. Field of the Invention
The present invention relates, generally, to a volatile negative differential resistance device using metal nanoparticles, and more particularly, to a volatile negative differential resistance device having an organic layer disposed between two metal electrodes, in which the organic layer is formed by uniformly dispersing metal nanoparticles having a diameter of about 10 nm or less in an organic material, thus realizing a volatile negative differential resistance phenomenon at room temperature upon application of voltage.
2. Description of the Related Art
In general, a negative differential resistance (“NDR”) device has been developed mainly using inorganic material. However, the NDR device using inorganic material is disadvantageous because it is manufactured through vacuum deposition requiring high temperature treatment, thus increasing manufacturing cost and complicating the manufacturing process. In particular, this NDR device is difficult to apply to flexible displays or flexible transistors, which have been thoroughly developed in recent years. Due to the drawbacks of the conventional inorganic NDR device, the development of NDR devices using organic material is receiving attention. NDR devices using organic material are capable of being manufactured through a simple wet process, such as spin coating at a low temperature.
The NDR device is classified as either a non-volatile NDR device or a volatile NDR device depending on whether recorded information is lost during an electrical power interruption. The volatile NDR device may be applied to various switching devices or logic devices such as mobile communication devices, delayed flip-flop circuits, etc., because of the volatile NDR properties thereof. However, almost all of the NDR devices using organic material developed to date exhibit a non-volatile NDR phenomenon. Thorough research into NDR devices exhibiting a volatile NDR phenomenon has not yet been conducted.
In this regard, U.S. Pat. No. 6,673,424 discloses a molecular electronic device, which includes gold nanoparticles and a self-assembled monolayer. However, the molecular electronic device does not teach the current-voltage properties of NDR.
In addition, U.S. Pat. No. 6,756,605 discloses a molecular scale electronic device, as a novel structure for improving volatile NDR. The molecular scale electronic device includes at least two conductive contacts and a monolayer of conductive organic material forming a conductive path between the contacts. However, this device suffers because it has a complicated manufacturing process, negates economical benefits and exhibits NDR only at a low temperature of about 60° K. Thus, because this device exhibits NDR only at about 60° K, it is difficult to actually use.